This invention relates to a photographing system for an endoscope and, more particularly, to a photographing system for an endoscope, in which observation light from an observation light source is used for observing a region of interest and photographing light from a photographing light source is used for photographing the region of interest.
In the usual photographing system for an endoscope, an observation light from an observation light source, for instance a halogen lamp, and a photographing light from a photographing light source, for instance an electric flash tube, can be introduced into a light guide of the endoscope. In an optical path, an optical path switching mirror is provided for directing the observation light to the light guide at the time of the observation and directing the photographing light to the light guide at the time of the photographing.
The problems in such an endoscopic photographing system are that the color reproduction of the photograph image is likely to be deteriorated, or the photograph image is likely to become blurred. The region for this is as follows. Usually, the optical path switching mirror is shifted simultaneously with or after the releasing of the shutter of the camera unit. However, at the time of the shifting of the mirror, a mechanical delay is involved, so that not only the photographing light but also the observation light is supplied after the releasing of the shutter. The dual exposure of the film to both photographing light and observation light blurs the resultant photograph image and also deteriorates the color reproduction thereof.
The object of the invention is to provide a photographing system for an endoscope, which prevents the exposure of a film in the camera unit to the observation light and permits exposure only to the photographing light at the time of the photographing, thus permitting a photograph of high clarity and good color reproduction to be obtained.